The invention relates to a heald for a heald shaft, having features as defined in the preamble of claim 1.
It has long been a desideratum to reduce the mass of weaving components which include heald shafts and healds. A reduction of the mass of weaving components is being sought after for significantly relieving the shaft drive and the shed forming machines, for saving energy and also, for achieving higher rpm's, while no increase in wear occurs but, on the contrary, even a reduction in wear may be obtained.
During shed-forming, the healds move the warp yarns, running through their yarn eyelet, out of the plane of the warp yarns, while other warp yarns running between the healds are moved by another other heald shaft in the same, or in the opposite direction. In this manner during each shed-forming process, the tensioned warp yarns run along the outer side of a heald. Such an occurrence causes an extreme stress on the yarns which may lead to warp yarn damage and, in an extreme case, to warp yarn breakage.
DE 43 36 362 C1 discloses a heald having a specially shaped yarn eyelet. The lead consists of a suitably shaped flat material. In the region of the yarn eyelet it is twisted in such a manner that the flat sides are oriented at an inclination to the warp yarn direction. The warp yarns which are situated between the healds and which do not run through the yarn eyelet, have to brush against the outer edges of the yarn eyelet and may thus be damaged.
The same document further discloses a heald which is not twisted in the region of its yarn eyelet, but in which the two webs bordering the yarn eyelet are merely bent in opposite directions. In this manner both lateral surfaces of the heald are, along their respective entire length, oriented in the warp yarn direction. It is noted, however, that because of bending the yarn eyelet webs, in the yarn eyelet at both the upper and the lower end a respective sharp corner is formed which may tend to provide a cut in a warp yarn. Further, the outward laterally bent legs do not prevent the adjoining healds from approaching one another so closely that one leg of an adjoining heald intersects the yarn eyelet of the other heald. This too, may result in the warp yarns to run up and down on the more or less sharp edges of the heald to thus cause yarn damage.
EP 0403429 discloses a heald made of a fiber-reinforced plastic. The heald body is provided with rounded edges in the region of the yarn eyelet, as well as in portions extending away therefrom. Similarly to the previously discussed heard, here too, adjoining yarn eyelets may overlap one another. This may cause damage to the yarns which run between the healds and which must pass by the yarn eyelet during shed-forming. This applies particularly at high operating speeds.
Accordingly, it is the object of the invention to provide an improved heald.